Congestion control and priority handling in device-to-device (D2D) communications

ABSTRACT

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first wireless communication device may iterate a value of a channel access counter (CAC) to a trigger value based at least in part on configuring the value of the CAC. In some aspects, the first wireless communication device may utilize a channel access mechanism to select a set of time-frequency resources for a transmission of a packet based at least in part on iterating the value of the CAC to the trigger value. In some aspects, the first wireless communication device may transmit the packet to a second wireless communication device via the set of time-frequency resources based at least in part on utilizing the channel access mechanism to select the set of time-frequency resources for the transmission. Numerous other aspects are provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/754,253, filed on Nov. 1, 2018, entitled “CONGESTION CONTROL ANDPRIORITY HANDLING IN DEVICE-TO-DEVICE (D2D) COMMUNICATIONS,” which ishereby expressly incorporated by reference herein.

INTRODUCTION

Aspects of the present disclosure generally relate to wirelesscommunication, and more particularly to techniques and apparatuses forcongestion control and priority handling in device-to-device (D2D)communications.

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power, and/or the like). Examples of such multiple-accesstechnologies include code division multiple access (CDMA) systems, timedivision multiple access (TDMA) systems, frequency-division multipleaccess (FDMA) systems, orthogonal frequency-division multiple access(OFDMA) systems, single-carrier frequency-division multiple access(SC-FDMA) systems, time division synchronous code division multipleaccess (TD-SCDMA) systems, and Long Term Evolution (LTE).LTE/LTE-Advanced is a set of enhancements to the Universal MobileTelecommunications System (UMTS) mobile standard promulgated by theThird Generation Partnership Project (3GPP).

A wireless communication network may include a number of base stations(BSs) that can support communication for a number of user equipment(UEs). A user equipment (UE) may communicate with a base station (BS)via the downlink and uplink. The downlink (or forward link) refers tothe communication link from the BS to the UE, and the uplink (or reverselink) refers to the communication link from the UE to the BS. As will bedescribed in more detail herein, a BS may be referred to as a Node B, agNB, an access point (AP), a radio head, a transmit receive point (TRP),a New Radio (NR) BS, a 5G Node B, and/or the like.

The above multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent user equipment to communicate on a municipal, national,regional, and even global level. New Radio (NR), which may also bereferred to as 5G, is a set of enhancements to the LTE mobile standardpromulgated by the Third Generation Partnership Project (3GPP). NR isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingorthogonal frequency division multiplexing (OFDM) with a cyclic prefix(CP) (CP-OFDM) on the downlink (DL), using CP-OFDM and/or SC-FDM (e.g.,also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) onthe uplink (UL), as well as supporting beamforming, multiple-inputmultiple-output (MIMO) antenna technology, and carrier aggregation.However, as the demand for mobile broadband access continues toincrease, there exists a need for further improvements in LTE and NRtechnologies. Preferably, these improvements should be applicable toother multiple access technologies and the telecommunication standardsthat employ these technologies.

SUMMARY

In some aspects, a method of wireless communication, performed by afirst wireless communication device, may include iterating a value of achannel access counter (CAC) to a trigger value based at least in parton configuring the value of the CAC. The method may include utilizing achannel access mechanism to select a set of time-frequency resources fora transmission of a packet based at least in part on iterating the valueof the CAC to the trigger value. The method may include transmitting thepacket to a second wireless communication device via the set oftime-frequency resources based at least in part on utilizing the channelaccess mechanism to select the set of time-frequency resources for thetransmission.

In some aspects, a first wireless communication device for wirelesscommunication may include memory and one or more processors operativelycoupled to the memory. The memory and the one or more processors may beconfigured to iterate a value of a channel access counter (CAC) to atrigger value based at least in part on configuring the value of theCAC. The memory and the one or more processors may be configured toutilize a channel access mechanism to select a set of time-frequencyresources for a transmission of a packet based at least in part oniterating the value of the CAC to the trigger value. The memory and theone or more processors may be configured to transmit the packet to asecond wireless communication device via the set of time-frequencyresources based at least in part on utilizing the channel accessmechanism to select the set of time-frequency resources for thetransmission.

In some aspects, a non-transitory computer-readable medium may store oneor more instructions for wireless communication. The one or moreinstructions, when executed by one or more processors of a firstwireless communication device, may cause the one or more processors toiterate a value of a channel access counter (CAC) to a trigger valuebased at least in part on configuring the value of the CAC. The one ormore instructions, when executed by the one or more processors, maycause the one or more processors to utilize a channel access mechanismto select a set of time-frequency resources for a transmission of apacket based at least in part on iterating the value of the CAC to thetrigger value. The one or more instructions, when executed by the one ormore processors, may cause the one or more processors to transmit thepacket to a second wireless communication device via the set oftime-frequency resources based at least in part on utilizing the channelaccess mechanism to select the set of time-frequency resources for thetransmission.

In some aspects, an apparatus for wireless communication may includemeans for iterating a value of a channel access counter (CAC) to atrigger value based at least in part on configuring the value of theCAC. The apparatus may include means for utilizing a channel accessmechanism to select a set of time-frequency resources for a transmissionof a packet based at least in part on iterating the value of the CAC tothe trigger value. The apparatus may include means for transmitting thepacket to another apparatus via the set of time-frequency resourcesbased at least in part on utilizing the channel access mechanism toselect the set of time-frequency resources for the transmission.

Aspects generally include a method, apparatus, system, computer programproduct, non-transitory computer-readable medium, user equipment, basestation, wireless communication device, and processing system assubstantially described herein with reference to and as illustrated bythe accompanying drawings and specification.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described hereinafter. The conceptionand specific examples disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present disclosure. Such equivalent constructions do notdepart from the scope of the appended claims. Characteristics of theconcepts disclosed herein, both their organization and method ofoperation, together with associated advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. Each of the figures is provided for the purpose ofillustration and description, and not as a definition of the limits ofthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can beunderstood in detail, a more particular description, briefly summarizedabove, may be had by reference to aspects, some of which are illustratedin the appended drawings. It is to be noted, however, that the appendeddrawings illustrate only certain typical aspects of this disclosure andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects. The samereference numbers in different drawings may identify the same or similarelements.

FIG. 1 is a block diagram conceptually illustrating an example of awireless communication network, in accordance with various aspects ofthe present disclosure.

FIG. 2 is a block diagram conceptually illustrating an example of a basestation in communication with a user equipment (UE) in a wirelesscommunication network, in accordance with various aspects of the presentdisclosure.

FIG. 3 is a diagram illustrating an example of congestion control andpriority handling in device-to-device (D2D) communications, inaccordance with various aspects of the present disclosure.

FIG. 4 is a diagram illustrating an example of congestion control andpriority handling in device-to-device (D2D) communications, inaccordance with various aspects of the present disclosure.

FIG. 5 is a diagram illustrating an example process performed, forexample, by a wireless communication device, in accordance with variousaspects of the present disclosure.

DETAILED DESCRIPTION

A wireless communication device, such as a user equipment (UE), a basestation (B S), and/or the like, may perform device-to-devicecommunications. For example, the wireless communication device mayperform sidelink communications with another wireless communicationdevice, where the sidelink communications include control informationand/or data. The control information may include information needed todecode the data, such as information that identifies a start resourceblock of the data, a length of allocation of resource blocks for thedata, a quantity of slots associated with the data, a modulation codingscheme (MCS) associated with the data, a link identifier, a destinationidentifier, and/or a source identifier for a wireless communicationdevice associated with the data (e.g., to facilitate feedback when thedata is not decoded), and/or the like.

In some D2D networks, such as vehicle-to-everything (V2X) networks orother D2D networks, the wireless communication device may use adistributed channel access mechanism (e.g., a random resource selectionmechanism, a listen-before-talk (LBT)-based selection mechanism, arequest-response (REQ-RESP)-based resource selection mechanism (e.g.,with transmit and/or receive yielding), a long-term sensing-basedresource selection mechanism, and/or the like) for time-frequencyresource selection for D2D communications.

Use of distributed channel access mechanisms can cause unavoidablecollisions among transmitters, such as devices using such a distributedchannel access mechanisms to access a channel. In some networks,resource overhead for channel contention may be based at least in parton which channel access mechanism is used. A probability of a collision(e.g., a spatial reuse of time-frequency resources) may depend on thechannel access mechanism that is used. For example, using a randomresource selection mechanism where multiple wireless communicationdevices select a set of time-frequency resources in a distributed mannermay result in a highest probability of a collision relative to otherchannel selection mechanisms, and may not increase a resource overheadfor channel contention. As another example, using an LBT-based selectionmechanism, where zones of guarded time-frequency resources are generatedfor various transmitters and/or receivers, results in a relatively lowprobability of a collision (on average) compared to other channelselection mechanisms. Continuing with the previous example and whenusing an LBT-based selection mechanism, a wireless communication devicetransmits in a first symbol or a third symbol based at least in part ona generated LBT counter, or transmits after performing random selectionon a fraction of time-frequency resources in a slot when contending forthe time-frequency resources. While some channel access mechanismsreduce a probability of collision when distributed channel accessmechanisms are used, the reduction results in high resource overhead.

Some techniques and apparatuses described herein provide for determiningchannel access priority for packets when wireless communication devicesassociated with a network are using distributed channel accessmechanisms. For example, some techniques and apparatuses describedherein provide for determining a manner in which to prioritize differentpackets in high channel load (e.g., congestion) environments. Thischannel access priority determination may be based at least in part on awindow of candidate resources. Packets with different priorities mayhave differently sized windows. A packet may be assigned a channelaccess counter (CAC) value based at least in part on the window of thepacket. Channel access for the packet may be based at least in part onincrementing the value of the CAC, so that packets with differentpriorities (and thus differently sized windows and different CACs) arehandled differently.

This improves a use of distributed channel access mechanisms to reduceor eliminate a probability of a collision among packets from differentwireless communication devices while using less resource overheadrelative to other channel access mechanisms. In addition, this improvesD2D communications of a wireless communication device by reducing oreliminating a probability of a collision. Further, this conservesprocessing resources of a wireless communication device that wouldotherwise be consumed as a result of a collision between packets fromthe wireless communication device and another wireless communicationdevice.

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art should appreciate that the scopeof the disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition toor other than the various aspects of the disclosure set forth herein. Itshould be understood that any aspect of the disclosure disclosed hereinmay be embodied by one or more elements of a claim.

Several aspects of telecommunication systems will now be presented withreference to various apparatuses and techniques. These apparatuses andtechniques will be described in the following detailed description andillustrated in the accompanying drawings by various blocks, modules,components, circuits, steps, processes, algorithms, and/or the like(collectively referred to as “elements”). These elements may beimplemented using hardware, software, or combinations thereof. Whethersuch elements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

It should be noted that while aspects may be described herein usingterminology commonly associated with 3G and/or 4G wireless technologies,aspects of the present disclosure can be applied in othergeneration-based communication systems, such as 5G and later, includingNR technologies.

FIG. 1 is a diagram illustrating a network 100 in which aspects of thepresent disclosure may be practiced. The network 100 may be an LTEnetwork, a 5G or NR network, future generation-based networks, and/orthe like. Wireless network 100 may include a number of BSs 110 (shown asBS 110 a, BS 110 b, BS 110 c, and BS 110 d) and other network entities.A BS is an entity that communicates with user equipment (UEs) and mayalso be referred to as a base station, a NR BS, a Node B, a gNB, a 5Gnode B (NB), an access point, a transmit receive point (TRP), and/or thelike. Each BS may provide communication coverage for a particulargeographic area. In 3GPP, the term “cell” can refer to a coverage areaof a BS and/or a BS subsystem serving this coverage area, depending onthe context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, afemto cell, and/or another type of cell. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having association with the femto cell (e.g.,UEs in a closed subscriber group (CSG)). ABS for a macro cell may bereferred to as a macro BS. ABS for a pico cell may be referred to as apico BS. A BS for a femto cell may be referred to as a femto BS or ahome BS. In the example shown in FIG. 1 , a BS 110 a may be a macro BSfor a macro cell 102 a, a BS 110 b may be a pico BS for a pico cell 102b, and a BS 110 c may be a femto BS for a femto cell 102 c. A BS maysupport one or multiple (e.g., three) cells. The terms “eNB”, “basestation”, “NR BS”, “gNB”, “TRP”, “AP”, “node B”, “5G NB”, and “cell” maybe used interchangeably herein.

In some examples, a cell may not necessarily be stationary, and thegeographic area of the cell may move according to the location of amobile BS. In some examples, the BSs may be interconnected to oneanother and/or to one or more other BSs or network nodes (not shown) inthe access network 100 through various types of backhaul interfaces suchas a direct physical connection, a virtual network, and/or the likeusing any suitable transport network.

Wireless network 100 may also include relay stations. A relay station isan entity that can receive a transmission of data from an upstreamstation (e.g., a BS or a UE) and send a transmission of the data to adownstream station (e.g., a UE or a BS). A relay station may also be aUE that can relay transmissions for other UEs. In the example shown inFIG. 1 , a relay station 110 d may communicate with macro BS 110 a and aUE 120 d in order to facilitate communication between BS 110 a and UE120 d. A relay station may also be referred to as a relay BS, a relaybase station, a relay, and/or the like.

Wireless network 100 may be a heterogeneous network that includes BSs ofdifferent types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/orthe like. These different types of BSs may have different transmit powerlevels, different coverage areas, and different impact on interferencein wireless network 100. For example, macro BSs may have a high transmitpower level (e.g., 5 to 40 Watts) whereas pico BSs, femto BSs, and relayBSs may have lower transmit power levels (e.g., 0.1 to 2 Watts).

A network controller 130 may couple to a set of BSs and may providecoordination and control for these BSs. Network controller 130 maycommunicate with the BSs via a backhaul. The BSs may also communicatewith one another, e.g., directly or indirectly via a wireless orwireline backhaul.

UEs 120 (e.g., 120 a, 120 b, 120 c) may be dispersed throughout wirelessnetwork 100, and each UE may be stationary or mobile. A UE may also bereferred to as an access terminal, a terminal, a mobile station, asubscriber unit, a station, and/or the like. A UE may be a cellularphone (e.g., a smart phone), a personal digital assistant (PDA), awireless modem, a wireless communication device, a handheld device, alaptop computer, a cordless phone, a wireless local loop (WLL) station,a tablet, a camera, a gaming device, a netbook, a smartbook, anultrabook, medical device or equipment, biometric sensors/devices,wearable devices (smart watches, smart clothing, smart glasses, smartwrist bands, smart jewelry (e.g., smart ring, smart bracelet)), anentertainment device (e.g., a music or video device, or a satelliteradio), a vehicular component or sensor, smart meters/sensors,industrial manufacturing equipment, a global positioning system device,or any other suitable device that is configured to communicate via awireless or wired medium.

Some UEs may be considered machine-type communication (MTC) or evolvedor enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEsinclude, for example, robots, drones, remote devices, sensors, meters,monitors, location tags, and/or the like, that may communicate with abase station, another device (e.g., remote device), or some otherentity. A wireless node may provide, for example, connectivity for or toa network (e.g., a wide area network such as Internet or a cellularnetwork) via a wired or wireless communication link. Some UEs may beconsidered Internet-of-Things (IoT) devices, and/or may be implementedas NB-IoT (narrowband internet of things) devices. Some UEs may beconsidered a Customer Premises Equipment (CPE). UE 120 may be includedinside a housing that houses components of UE 120, such as processorcomponents, memory components, and/or the like.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular RAT andmay operate on one or more frequencies. A RAT may also be referred to asa radio technology, an air interface, and/or the like. A frequency mayalso be referred to as a carrier, a frequency channel, and/or the like.Each frequency may support a single RAT in a given geographic area inorder to avoid interference between wireless networks of different RATs.In some cases, NR or 5G RAT networks may be deployed.

As shown in FIG. 1 , the UE 120 may include a communication manager 140.As described in more detail elsewhere herein, the communication manager140 may iterate a value of a channel access counter (CAC) based at leastin part on a configured value of the CAC, may determine that the valueof the CAC satisfies a trigger value, may utilize a channel accessmechanism to select a set of time-frequency resources for a transmissionof a packet based at least in part on the value of the CAC satisfyingthe trigger value, and may transmit the packet to a second wirelesscommunication device via the selected set of time-frequency resourcesbased at least in part on utilizing the channel access mechanism toselect the set of time-frequency resources for the transmission.Additionally, or alternatively, the communication manager 140 mayperform one or more other operations described herein.

Similarly, the base station 110 may include a communication manager 150.As described in more detail elsewhere herein, the communication manager150 may iterate a value of a CAC based at least in part on a configuredvalue of the CAC, may determine that the value of the CAC satisfies atrigger value, may utilize a channel access mechanism to select a set oftime-frequency resources for a transmission of a packet based at leastin part on the value of the CAC satisfying the trigger value, and maytransmit the packet to a second wireless communication device via theselected set of time-frequency resources based at least in part onutilizing the channel access mechanism to select the set oftime-frequency resources for the transmission. Additionally, oralternatively, the communication manager 150 may perform one or moreother operations described herein.

As shown by reference number 160, BS 110 may iterate a value of a CACbased at least in part on a configured value of the CAC, may determinethat the value of the CAC satisfies a trigger value, may utilize achannel access mechanism to select a set of time-frequency resources fora transmission of a packet based at least in part on the value of theCAC satisfying the trigger value, and may transmit the packet to asecond wireless communication device via the selected set oftime-frequency resources based at least in part on utilizing the channelaccess mechanism to select the set of time-frequency resources for thetransmission, as described elsewhere herein. For example, BS 110 mayperform these operations for congestion control and priority handling inD2D communications.

As shown by reference number 170, UE 120 may iterate a value of a CACbased at least in part on a configured value of the CAC, may determinethat the value of the CAC satisfies a trigger value, may utilize achannel access mechanism to select a set of time-frequency resources fora transmission of a packet based at least in part on the value of theCAC satisfying the trigger value, and may transmit the packet to asecond wireless communication device via the selected set oftime-frequency resources based at least in part on utilizing the channelaccess mechanism to select the set of time-frequency resources for thetransmission, as described elsewhere herein. For example, UE 120 mayperform these operations for congestion control and priority handling inD2D communications.

As indicated above, FIG. 1 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 1 .

FIG. 2 shows a block diagram of a design 200 of base station 110 and UE120, which may be one of the base stations and one of the UEs in FIG. 1. Base station 110 may be equipped with T antennas 234 a through 234 t,and UE 120 may be equipped with R antennas 252 a through 252 r, where ingeneral T≥1 and R≥1.

At base station 110, a transmit processor 220 may receive data from adata source 212 for one or more UEs, select one or more modulation andcoding schemes (MCS) for each UE based at least in part on channelquality indicators (CQIs) received from the UE, process (e.g., encodeand modulate) the data for each UE based at least in part on the MCS(s)selected for the UE, and provide data symbols for all UEs. Transmitprocessor 220 may also process system information (e.g., for semi-staticresource partitioning information (SRPI) and/or the like) and controlinformation (e.g., CQI requests, grants, upper layer signaling, and/orthe like) and provide overhead symbols and control symbols. Transmitprocessor 220 may also generate reference symbols for reference signals(e.g., the cell-specific reference signal (CRS)) and synchronizationsignals (e.g., the primary synchronization signal (PSS) and secondarysynchronization signal (SSS)). A transmit (TX) multiple-inputmultiple-output (MIMO) processor 230 may perform spatial processing(e.g., precoding) on the data symbols, the control symbols, the overheadsymbols, and/or the reference symbols, if applicable, and may provide Toutput symbol streams to T modulators (MODs) 232 a through 232 t. Eachmodulator 232 may process a respective output symbol stream (e.g., forOFDM and/or the like) to obtain an output sample stream. Each modulator232 may further process (e.g., convert to analog, amplify, filter, andupconvert) the output sample stream to obtain a downlink signal. Tdownlink signals from modulators 232 a through 232 t may be transmittedvia T antennas 234 a through 234 t, respectively. According to variousaspects described in more detail below, the synchronization signals canbe generated with location encoding to convey additional information.

At UE 120, antennas 252 a through 252 r may receive the downlink signalsfrom base station 110 and/or other base stations and may providereceived signals to demodulators (DEMODs) 254 a through 254 r,respectively. Each demodulator 254 may condition (e.g., filter, amplify,downconvert, and digitize) a received signal to obtain input samples.Each demodulator 254 may further process the input samples (e.g., forOFDM and/or the like) to obtain received symbols. A MIMO detector 256may obtain received symbols from all R demodulators 254 a through 254 r,perform MIMO detection on the received symbols if applicable, andprovide detected symbols. A receive processor 258 may process (e.g.,demodulate and decode) the detected symbols, provide decoded data for UE120 to a data sink 260, and provide decoded control information andsystem information to a controller/processor 280. A channel processormay determine reference signal received power (RSRP), received signalstrength indicator (RSSI), reference signal received quality (RSRQ),channel quality indicator (CQI), and/or the like. In some aspects, oneor more components of UE 120 may be included in a housing.

On the uplink, at UE 120, a transmit processor 264 may receive andprocess data from a data source 262 and control information (e.g., forreports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) fromcontroller/processor 280. Transmit processor 264 may also generatereference symbols for one or more reference signals. The symbols fromtransmit processor 264 may be precoded by a TX MIMO processor 266 ifapplicable, further processed by modulators 254 a through 254 r (e.g.,for DFT-s-OFDM, CP-OFDM, and/or the like), and transmitted to basestation 110. At base station 110, the uplink signals from UE 120 andother UEs may be received by antennas 234, processed by demodulators232, detected by a MIMO detector 236 if applicable, and furtherprocessed by a receive processor 238 to obtain decoded data and controlinformation sent by UE 120. Receive processor 238 may provide thedecoded data to a data sink 239 and the decoded control information tocontroller/processor 240. Base station 110 may include communicationunit 244 and communicate to network controller 130 via communicationunit 244. Network controller 130 may include communication unit 294,controller/processor 290, and memory 292.

Controller/processor 240 of base station 110, controller/processor 280of UE 120, and/or any other component(s) of FIG. 2 may perform one ormore techniques associated with congestion control and priority handlingin D2D communications, as described in more detail elsewhere herein. Forexample, controller/processor 240 of base station 110,controller/processor 280 of UE 120, and/or any other component(s) ofFIG. 2 may perform or direct operations of, for example, process 500 ofFIG. 5 , and/or other processes as described herein. Memories 242 and282 may store data and program codes for base station 110 and UE 120,respectively. A scheduler 246 may schedule UEs for data transmission onthe downlink and/or uplink.

In some aspects, and as shown by reference number 296, the UE 120 mayinclude means for iterating a value of a CAC based at least in part on aconfigured value of the CAC, means for determining that the value of theCAC satisfies a trigger value, means for utilizing a channel accessmechanism to select a set of time-frequency resources for a transmissionof a packet based at least in part on the value of the CAC satisfyingthe trigger value, means for transmitting the packet to a secondwireless communication device via the selected set of time-frequencyresources based at least in part on utilizing the channel accessmechanism to select the set of time-frequency resources for thetransmission, means for configuring the value of the CAC for the packetprior to iterating the value of the CAC, means for determining, prior toiterating the value of the CAC, a quantity of candidate resources thatis available in a slot, wherein a candidate resource has a size equal toa quantity of time-frequency resources to be used for the transmissionof the packet, means for determining that the packet is ready to betransmitted prior to iterating the value of the CAC, means fordetermining, based at least in part on determining that the packet isready to be transmitted, a transmission window for the transmission ofthe packet, means for utilizing the channel access mechanism to selectthe set of time-frequency resources for the transmission of the packetbased at least in part on iterating the value of the CAC to the triggervalue, means for iterating the value of the CAC by a fractional value ofa quantity of time-frequency resources available in a slot, means foriterating the value of the CAC by a multiple of a fractional value of aquantity of time-frequency resources available in a slot, and/or thelike. Additionally, or alternatively, the UE 120 may include means forperforming one or more other operations described herein. In someaspects, such means may include the communication manager 140.Additionally, or alternatively, such means may include one or morecomponents of the UE 120 described in connection with FIG. 2 .

In some aspects, and as shown by reference number 298, the base station110 may include means for iterating a value of a CAC based at least inpart on a configured value of the CAC, means for determining that thevalue of the CAC satisfies a trigger value, means for utilizing achannel access mechanism to select a set of time-frequency resources fora transmission of a packet based at least in part on the value of theCAC satisfying the trigger value, means for transmitting the packet to asecond wireless communication device via the selected set oftime-frequency resources based at least in part on utilizing the channelaccess mechanism to select the set of time-frequency resources for thetransmission, means for configuring the value of the CAC for the packetprior to iterating the value of the CAC, means for determining, prior toiterating the value of the CAC, a quantity of candidate resources thatis available in a slot, wherein a candidate resource has a size equal toa quantity of time-frequency resources to be used for the transmissionof the packet, means for determining that the packet is ready to betransmitted prior to iterating the value of the CAC, means fordetermining, based at least in part on determining that the packet isready to be transmitted, a transmission window for the transmission ofthe packet, means for utilizing the channel access mechanism to selectthe set of time-frequency resources for the transmission of the packetbased at least in part on iterating the value of the CAC to the triggervalue, means for iterating the value of the CAC by a fractional value ofa quantity of time-frequency resources available in a slot, means foriterating the value of the CAC by a multiple of a fractional value of aquantity of time-frequency resources available in a slot, and/or thelike. Additionally, or alternatively, the base station 110 may includemeans for performing one or more other operations described herein. Insome aspects, such means may include the communication manager 150. Insome aspects, such means may include one or more components of the basestation 110 described in connection with FIG. 2 .

As indicated above, FIG. 2 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 2 .

FIG. 3 is a diagram illustrating an example 300 of congestion controland priority handling in D2D communications, in accordance with variousaspects of the present disclosure. As shown in FIG. 3 , example 300includes a first wireless communication device (e.g., a first BS 110, afirst UE 120, and/or the like) and a second wireless communicationdevice (e.g., a second BS 110, a second UE 120, and/or the like).

As shown by reference number 310, the first wireless communicationdevice may iterate a value of a channel access counter (CAC) based atleast in part on configuring the value of the CAC. For example, thefirst wireless communication device may configure the value of the CAC(e.g., by storing a starting value for the CAC in memory resourcesassociated with the first wireless communication device) prior toiterating the value of the CAC. As shown by reference number 320, thefirst wireless communication device may determine that the value of theCAC satisfies a trigger value. In some aspects, the trigger value may bebased at least in part on a size of a transmission window for a packet.In some aspects, a starting value for the CAC may be based at least inpart on a size of a transmission window for a packet, as describedelsewhere herein. A size of a transmission window may refer to aquantity of time-frequency resources associated with a transmissionwindow. In some aspects, the starting value may be zero, and the triggervalue may be a value between zero and the size of the transmissionwindow.

In some aspects, the first wireless communication device may determinethat a packet is ready to be transmitted. For example, the firstwireless communication device (e.g., a component of the first wirelesscommunication device and/or an application associated with the firstwireless communication device) may generate a packet and the firstwireless communication device may determine that the packet is ready tobe transmitted based at least in part on the first wirelesscommunication device generating the packet. In some aspects, the firstwireless communication device may determine that the packet is ready tobe transmitted prior to generating the value of the CAC and/or iteratingthe value of the CAC.

In some aspects, the first wireless communication device may determine aquantity of candidate resources that is available in a slot. Forexample, the first wireless communication device may determine thequantity of candidate resources that is available prior to generatingthe value of the CAC, prior to iterating the value of the CAC, based atleast in part on determining that the packet is ready to be transmitted,and/or the like. In some aspects, a candidate resource represents a setof time-frequency resources that is available in a slot. In someaspects, a candidate resource may have a size that is equal to aquantity of time-frequency resources to be used for a transmission ofthe packet. For example, if 10 resource blocks are to be used for atransmission of the packet, then one candidate resource may represent 10available resource blocks in a slot. Continuing with the previousexample, if 20 resources blocks are available in a slot, then the firstwireless communication device may determine that two candidate resourcesare available in the slot.

In some aspects, the first wireless communication device may determine atransmission window for the transmission of the packet. For example, thefirst wireless communication device may determine the transmissionwindow based at least in part on determining that the packet is ready tobe transmitted, prior to generating the value of the CAC, prior toiterating the value of the CAC, and/or the like. In some aspects, a sizeof the transmission window may be based at least in part on the quantityof candidate resources that is available in the slot. For example, ifthe first wireless communication device determines that two candidateresources are available in the slot, then the first wirelesscommunication device may determine a transmission window for the packetthat has a size of two candidate resources. Additionally, oralternatively, a size of the transmission window may be based at leastin part on a quantity of slots associated with a transmission of thepacket (e.g., a quantity of slots to be used for the transmission).

Additionally, or alternatively, and as another example, the firstwireless communication device may determine a size of the transmissionwindow based at least in part on a channel busy ratio (CBR) for a slotto be used for a transmission of the packet (e.g., a higher relative CBRmay be associated with a larger sized transmission window), a quality ofservice (QoS) associated with the packet (e.g., a higher QoS may beassociated with a smaller sized transmission window), and/or the like.Additionally, or alternatively, and as another example, the firstwireless communication device may be pre-configured with information(e.g., via a radio resource control (RRC) configuration) that identifiesa mapping between various quantities of candidate resources availableand corresponding transmission window sizes.

In some aspects, a size of the transmission window may be based at leastin part on a priority associated with the packet. For example, differentpriority packets may be associated with different sized transmissionwindows. Continuing with the previous example, the first wirelesscommunication device may determine a smaller transmission window (e.g.,with a smaller relative quantity of time-frequency resources) for apacket with a higher priority relative to another packet. This mayincrease a quantity of potential opportunities to transmit a packetrelative to a larger transmission window by reducing a quantity ofavailable time-frequency resources that need to be available to transmita packet. In some aspects, the first wireless communication device maybe configured (e.g., pre-configured) with information (e.g., via an RRCconfiguration) that identifies a mapping between various priorities andcorresponding sizes of transmission windows.

In some aspects, the first wireless communication device may generatethe CAC and/or the value of the CAC. For example, the first wirelesscommunication device may store information identifying the CAC in memoryresources, may store information identifying a starting value of theCAC, a current value of the CAC, a trigger value of the CAC, and/or thelike in the memory resources. In some aspects, the first wirelesscommunication device may generate different CACs and/or different valuesfor different CACs for different packets, for different sets of packets,and/or the like.

In some aspects, the first wireless communication device may determine astarting value for the CAC. For example, the first wirelesscommunication device may determine the starting value after, or inassociation with, configuring the value of the CAC, prior to iteratingthe value of the CAC, and/or the like. In some aspects, the startingvalue may be equal to zero (e.g., when the first wireless communicationdevice is to iterate the value of the CAC in an increasing manner), maybe equal to the quantity of candidate resources that is available in aslot (e.g., when the first wireless communication device is to iteratethe value of the CAC in a decreasing manner), and/or the like. In someaspects, the first wireless communication device may determine differentstarting values for different CACs (e.g., associated with differentpackets, with different priorities, and/or the like).

In some aspects, the first wireless communication device may iterate thevalue of the CAC after, or based at least in part on, determining thestarting value for the CAC. In some aspects, the first wirelesscommunication device may iterate the value of the CAC by an amount equalto a quantity of elapsed candidate resources available in a slot. Forexample, if two available candidate resources have elapsed in a slot,then the first wireless communication device may iterate the value ofthe CAC by two. In some aspects, the first wireless communication devicemay iterate the value of the CAC by a quantity of elapsed availableslots associated with a transmission window. For example, if atransmission of a packet is to use one or more slots (e.g., one or moreslots are associated with a transmission window for the packet), thenthe first wireless communication device may iterate the value of thecounter by a quantity of elapsed available slots. In some aspects, thefirst wireless communication device may iterate the value of the CACbased at least in part on a CBR for a slot to be used for thetransmission of the packet (e.g., the first wireless communicationdevice may iterate the value of the CAC by a lower relative value for ahigher relative CBR), a priority of the packet (e.g., the first wirelesscommunication device may iterate the value by a higher relative valuefor a higher relative priority), a quality of service (QoS) associatedwith the packet (e.g., the first wireless communication device mayiterate the value of the CAC by a higher relative value for a higherrelative QoS), and/or the like.

In some aspects, the first wireless communication device may iterate thevalue of the CAC by a fractional value of a quantity of time-frequencyresources available in a slot. For example, the first wirelesscommunication device may iterate the value of the CAC by a fractionalvalue, rather than by an integer value. In some aspects, the fractionalvalue may be based at least in part on a quantity of availabletime-frequency resources in a slot that has an amount of energy and/orpower (e.g., in decibels (dBm)) that satisfies a configured threshold.For example, if 40 percent (e.g., 0.4) of the time-frequency resourcesin a slot have an amount of energy and/or power that is less than athreshold, then the first wireless communication device may iterate thevalue of the CAC by 0.6 (e.g., 1.0-0.4) based at least in part on 60% ofthe time-frequency resources having an amount of energy that is greaterthan or equal to the threshold, rather than pausing the iterating of thevalue.

In some aspects, whether the first wireless communication deviceiterates the value of the CAC or pauses the iteration of the value ofthe CAC when a fractional amount of time-frequency resources (e.g., afractional amount of a total quantity of time-frequency resources)associated with a candidate resource are available may be based at leastin part on the fractional amount satisfying a threshold. For example,the first wireless communication device may pause the iteration of thevalue (e.g., may not iterate the value) if the fractional amount failsto satisfy a threshold, and may iterate the value (e.g., may not pausethe iteration of the value) if the fractional amount satisfies thethreshold. In some aspects, the threshold may be pre-configured to thefirst wireless communication device via an RRC configuration.

In some aspects, the first wireless communication device may iterate thevalue of the CAC by a multiple of a fractional value of a quantity oftime-frequency resources available in a slot. For example, if afractional amount of a quantity of time-frequency resources is availablein a slot (e.g., associated with a candidate resource), then the firstwireless communication device may iterate the value of the CAC by amultiple of the fractional value (e.g., by two times the fractionalvalue, three times the fractional value, and/or so forth).

In some aspects, the multiple may be a fractional value or anon-fractional value. In some aspects, the multiple may be based atleast in part on a priority associated with the packet. For example,different priorities may be associated with different multiples (e.g., ahigher relative priority may be associated with a higher relativemultiple). In some aspects, the multiple may be based at least in parton a QoS associated with the packet. For example, different QoS may beassociated with different multiples (e.g., a higher relative QoS may beassociated with a higher relative multiple). In some aspects, themultiple may be configured (e.g., pre-configured) to the first wirelesscommunication device via an RRC configuration.

In some aspects, the first wireless communication device may iterate thevalue of the CAC by increasing the value of the CAC or by decreasing thevalue of the CAC. In some aspects, the first wireless communicationdevice may iterate the value of the CAC to a trigger value. For example,satisfaction of the trigger value may cause the first wirelesscommunication device to perform one or more actions, as describedelsewhere herein.

In some aspects, if candidate resources are not available, then thefirst wireless communication device may pause the iterating of the valueof the CAC. For example, when an unavailable candidate resource elapses,then the first wireless communication device may not iterate the valueof the CAC. In some aspects, if the first wireless communication devicehas paused the iterating of the CAC, then the first wirelesscommunication device may resume the iterating of the value of the CACwhen candidate resources become available.

As shown by reference number 330, the first wireless communicationdevice may utilize a channel access mechanism to select a set oftime-frequency resources for a transmission of the packet. For example,the first wireless communication device may utilize the channel accessmechanism based at least in part on iterating the value of the CAC tothe trigger value or based at least in part on the value satisfying atrigger value (e.g., satisfying a threshold defined based at least inpart on the trigger value). In some aspects, a channel access mechanismmay include a random resource selection mechanism, an LBT-basedmechanism, and/or the like.

As shown by reference number 340, the first wireless communicationdevice may transmit the packet to the second wireless communicationdevice via the set of time-frequency resources. For example, the firstwireless communication device may transmit the packet to the secondwireless communication device based at least in part on utilizing thechannel access mechanism to select the set of time-frequency resourcesfor a transmission of the packet.

As indicated above, FIG. 3 is provided as an example. Other examples maydiffer from what is described with respect to FIG. 3 .

FIG. 4 is a diagram illustrating an example 400 of congestion controland priority handling in D2D communications, in accordance with variousaspects of the present disclosure. FIG. 4 shows different sizedtransmission windows (W1 through W3) that may be used for packetsassociated with different priorities.

As shown by reference number 410, a first sized transmission window W1may be used for packets associated with a first priority (e.g., priority1). For example, priority 1 packets may have a higher priority relativeto priority 2 packets and priority 3 packets described below. As such,and as further shown by reference number 410, W1 may be associated witha smaller quantity of time-frequency resources than W2 (associated withpriority 2 packets) and W3 (associated with priority 3 packets). In someaspects, the smaller sized transmission window W1 may result in awireless communication device transmitting priority 1 packets prior topriority 2 packets and/or priority 3 packets (e.g., based on fasteriteration of the value of the CAC associated with priority 1 packetsrelative to priority 2 packets and priority 3 packets).

As shown by reference number 420, W2 may be used for priority 2 packets.For example, priority 2 packets may have a higher priority relative topriority 3 packets and may have a lower priority relative to priority 1packets. As such, and as further shown by reference number 420, W2 maybe associated with a smaller quantity of time-frequency resources thanW3, but with a larger quantity of time-frequency resources than W1. Insome aspects, the smaller sized transmission window W2 may result in awireless communication device transmitting priority 2 packets prior topriority 3 packets (e.g., based on faster iteration of the value of theCAC associated with priority 2 packets relative to priority 3 packets).

As shown by reference number 430, W3 may be used for priority 3 packets.For example, priority 3 packets may have a lower priority relative topriority 1 packets and priority 2 packets. As such, and as further shownby reference number 430, W3 may be associated with a smaller quantity oftime-frequency resources than W1 and W2. In some aspects, the largersized transmission window may result in a wireless communication devicetransmitting priority 3 packets after priority 1 packets and afterpriority 2 packets (e.g., based on slower iteration of the value of theCAC associated with the priority 3 packets relative to priority 1packets and priority 2 packets).

In some aspects, and as described elsewhere herein, a size of atransmission window may be based at least in part on a CBR associatedwith a slot. For example, the relative sizes of the transmission windowsshown in FIG. 4 may be based at least in part on a CBR value associatedwith a slot to be used for a transmission of packets (e.g., priority 1packets, priority 2 packets, and/or priority 3 packets).

As indicated above, FIG. 4 is provided as an example. Other examples maydiffer from what is described with respect to FIG. 4 .

FIG. 5 is a diagram illustrating an example process 500 performed, forexample, by a first wireless communication device, in accordance withvarious aspects of the present disclosure. Example process 500 is anexample where a first wireless communication device (e.g., BS 110, UE120, and/or the like) performs congestion control and priority handlingin D2D communications.

As shown in FIG. 5 , in some aspects, process 500 may include iteratinga value of a channel access counter (CAC) based at least in part onconfiguring the value of the CAC (block 510). For example, the firstwireless communication device (e.g., using controller/processor 240,controller/processor 280, and/or the like) may iterate a value of achannel access counter (CAC) based at least in part on configuring thevalue of the CAC, as described elsewhere herein.

As further shown in FIG. 5 , in some aspects, process 500 may includedetermining that the value of the CAC satisfies a trigger value (block520). For example, the first wireless communication device (e.g., usingcontroller/processor 240, controller/processor 280, and/or the like) maydetermine that the value of the CAC satisfies a trigger value (e.g., athreshold defined by a trigger value). In some aspects, this may bebased at least in part on iterating the value of the CAC to the triggervalue.

As further shown in FIG. 5 , in some aspects, process 500 may includeutilizing a channel access mechanism to select a set of time-frequencyresources for a transmission of a packet based at least in part on thevalue of the CAC satisfying the trigger value (block 530). For example,the first wireless communication device (e.g., usingcontroller/processor 240, controller/processor 280, and/or the like) mayutilize a channel access mechanism to select a set of time-frequencyresources for a transmission of a packet based at least in partiterating the value of the CAC satisfying the trigger value, asdescribed elsewhere herein.

As further shown in FIG. 5 , in some aspects, process 500 may includetransmitting the packet to a second wireless communication device viathe set of time-frequency resources based at least in part on utilizingthe channel access mechanism to select the set of time-frequencyresources for the transmission (block 540). For example, the firstwireless communication device (e.g., using controller/processor 240,transmit processor 220, TX MIMO processor 230, MOD 232, antenna 234,controller/processor 280, transmit processor 264, TX MIMO processor 266,MOD 254, antenna 252, and/or the like) may transmit the packet to asecond wireless communication device via the set of time-frequencyresources based at least in part on utilizing the channel accessmechanism to select the set of time-frequency resources for thetransmission, as described elsewhere herein.

Process 500 may include additional aspects, such as any single aspect orany combination of aspects described below and/or in connection with oneor more other processes described elsewhere herein.

In a first aspect, process 500 includes configuring the value of the CACfor the packet prior to iterating the value of the CAC.

In a second aspect, alone or in combination with the first aspect,process 500 includes determining, prior to iterating the value of theCAC, a quantity of candidate resources that is available in a slot,wherein a candidate resource has a size equal to a quantity oftime-frequency resources to be used for the transmission of the packet.

In a third aspect, alone or in combination with one or more of the firstand second aspects, process 500 includes determining that the packet isready to be transmitted prior to iterating the value of the CAC; anddetermining, based at least in part on determining that the packet isready to be transmitted, a transmission window for the transmission ofthe packet.

In a fourth aspect, alone or in combination with one or more of thefirst through third aspects, a size of the transmission window is basedat least in part on at least one of: the quantity of candidate resourcesthat is available in the slot, a quantity of slots associated with thetransmission, or a combination of the quantity of candidate resourcesthat is available in the slot and the quantity of slots associated withthe transmission.

In a fifth aspect, alone or in combination with one or more of the firstthrough fourth aspects, the size of the transmission window is based atleast in part on at least one of: a priority associated with the packet,a quality of service (QoS) value associated with the packet, or acombination of the priority and the QoS value.

In a sixth aspect, alone or in combination with one or more of the firstthrough fifth aspects, the priority associated with the packet isidentified in a radio resource control (RRC) configuration received froma third wireless communication device.

In a seventh aspect, alone or in combination with one or more of thefirst through sixth aspects, the value of the CAC has a starting valuethat is based at least in part on the size of the transmission window.

In an eighth aspect, alone or in combination with one or more of thefirst through seventh aspects, the trigger value is between zero and thesize of the transmission window.

In a ninth aspect, alone or in combination with one or more of the firstthrough eighth aspects, iterating the value of the CAC comprises:iterating the value of the CAC by an amount equal to at least one of: aquantity of elapsed candidate resources available in a slot, a quantityof elapsed available slots associated with a transmission window, or acombination of the quantity of elapsed candidate resources and thequantity of elapsed available slots.

In a tenth aspect, alone or in combination with one or more of the firstthrough ninth aspects, utilizing the channel access mechanism comprises:utilizing the channel access mechanism to select the set oftime-frequency resources for the transmission of the packet based atleast in part on iterating the value of the CAC to the trigger value.

In an eleventh aspect, alone or in combination with one or more of thefirst through tenth aspects, the channel access mechanism includes atleast one of: a random resource selection mechanism, alisten-before-talk (LBT)-based mechanism, or a combination of the randomresource selection mechanism and the LBT-based mechanism.

In a twelfth aspect, alone or in combination with one or more of thefirst through eleventh aspects, iterating the value of the CACcomprises: iterating the value of the CAC by a fractional value of aquantity of time-frequency resources available in a slot.

In a thirteenth aspect, alone or in combination with one or more of thefirst through twelfth aspects, the fractional value is based at least inpart on a quantity of available time-frequency resources in the slotthat has an amount of energy that satisfies a configured threshold.

In a fourteenth aspect, alone or in combination with one or more of thefirst through thirteenth aspects, the configured threshold ispre-configured via a radio resource control (RRC) configuration.

In a fifteenth aspect, alone or in combination with one or more of thefirst through fourteenth aspects, iterating the value of the CACcomprises: iterating the value of the CAC by a multiple of a fractionalvalue of a quantity of time-frequency resources available in a slot.

In a sixteenth aspect, alone or in combination with one or more of thefirst through fifteenth aspects, the multiple is a non-fractional value.

In a seventeenth aspect, alone or in combination with one or more of thefirst through sixteenth aspects, the multiple is another fractionalvalue.

In an eighteenth aspect, alone or in combination with one or more of thefirst through seventeenth aspects, the multiple is based at least inpart on at least one of: a priority associated with the packet, aquality of service (QoS) value associated with the packet, or acombination of the priority and the QoS value.

In a nineteenth aspect, alone or in combination with one or more of thefirst through eighteenth aspects, the priority associated with thepacket, the QoS value associated with the packet, or the multiple arepre-configured via a radio resource control (RRC) configuration.

In a twentieth aspect, alone or in combination with one or more of thefirst through nineteenth aspects, a size of a transmission window fortransmission of the packet, or a multiple of a fractional value of aquantity of time-frequency resources available in a slot, are based atleast in part on at least one of: a channel busy ratio (CBR) for theslot to be used for the transmission of the packet, a priority of thepacket, a quality of service (QoS) value of the packet, or a combinationof the CBR for the slot, the priority of the packet, and the QoS valueof the packet.

In a twenty-first aspect, alone or in combination with one or more ofthe first through twentieth aspects, an amount by which the value of theCAC is iterated is based at least in part on at least one of: a channelbusy ratio (CBR) for a slot to be used for the transmission of thepacket, a priority of the packet, or a combination of the CBR for theslot and the priority of the packet.

Although FIG. 5 shows example blocks of process 500, in some aspects,process 500 may include additional blocks, fewer blocks, differentblocks, or differently arranged blocks than those depicted in FIG. 5 .Additionally, or alternatively, two or more of the blocks of process 500may be performed in parallel.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the aspects to the preciseform disclosed. Modifications and variations may be made in light of theabove disclosure or may be acquired from practice of the aspects.

As used herein, the term “component” is intended to be broadly construedas hardware, firmware, or a combination of hardware and software. Asused herein, a processor is implemented in hardware, firmware, or acombination of hardware and software.

Some aspects are described herein in connection with thresholds. As usedherein, satisfying a threshold may refer to a value being greater thanthe threshold, greater than or equal to the threshold, less than thethreshold, less than or equal to the threshold, equal to the threshold,not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods, described herein, maybe implemented in different forms of hardware, firmware, or acombination of hardware and software. The actual specialized controlhardware or software code used to implement these systems and/or methodsis not limiting of the aspects. Thus, the operation and behavior of thesystems and/or methods were described herein without reference tospecific software code—it being understood that software and hardwarecan be designed to implement the systems and/or methods based, at leastin part, on the description herein.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various aspects. In fact, many ofthese features may be combined in ways not specifically recited in theclaims and/or disclosed in the specification. Although each dependentclaim listed below may directly depend on only one claim, the disclosureof various aspects includes each dependent claim in combination withevery other claim in the claim set. A phrase referring to “at least oneof” a list of items refers to any combination of those items, includingsingle members. As an example, “at least one of: a, b, or c” is intendedto cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combinationwith multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c,a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering ofa, b, and c).

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Furthermore,as used herein, the terms “set” and “group” are intended to include oneor more items (e.g., related items, unrelated items, a combination ofrelated and unrelated items, and/or the like), and may be usedinterchangeably with “one or more.” Where only one item is intended, thephrase “only one” or similar language is used. Also, as used herein, theterms “has,” “have,” “having,” and/or the like are intended to beopen-ended terms. Further, the phrase “based on” is intended to mean“based, at least in part, on” unless explicitly stated otherwise.

What is claimed is:
 1. A method of wireless communication performed by afirst wireless communication device, comprising: iterating a value of achannel access counter (CAC) based at least in part on a starting valueof the CAC, wherein the starting value is based at least in part on asize of a transmission window; determining that the value of the CACsatisfies a trigger value; utilizing a channel access mechanism toselect a set of time-frequency resources for a transmission of a packetbased at least in part on the value of the CAC satisfying the triggervalue; and transmitting the packet to a second wireless communicationdevice via the selected set of time-frequency resources.
 2. The methodof claim 1, further comprising: configuring the value of the CAC for thepacket prior to iterating the value of the CAC.
 3. The method of claim1, further comprising: determining, prior to iterating the value of theCAC, a quantity of candidate resources that is available in a slot,wherein a candidate resource has a size equal to a quantity oftime-frequency resources to be used for the transmission of the packet.4. The method of claim 1, further comprising: determining that thepacket is ready to be transmitted prior to iterating the value of theCAC; and determining, based at least in part on determining that thepacket is ready to be transmitted, the transmission window for thetransmission of the packet.
 5. The method of claim 1, wherein the sizeof the transmission window is based at least in part on at least one of:a quantity of candidate resources that is available in a slot, aquantity of slots associated with the transmission, or a combination ofthe quantity of candidate resources that is available in the slot andthe quantity of slots associated with the transmission.
 6. The method ofclaim 1, wherein the size of the transmission window is based at leastin part on at least one of: a priority associated with the packet, aquality of service (QoS) value associated with the packet, or acombination of the priority and the QoS value.
 7. The method of claim 6,wherein the priority associated with the packet is identified in a radioresource control (RRC) configuration received from a third wirelesscommunication device.
 8. The method of claim 1, wherein the triggervalue is between zero and the size of the transmission window.
 9. Themethod of claim 1, wherein iterating the value of the CAC comprises:iterating the value of the CAC by an amount equal to at least one of: aquantity of elapsed candidate resources available in a slot, a quantityof elapsed available slots associated with the transmission window, or acombination of the quantity of elapsed candidate resources and thequantity of elapsed available slots.
 10. The method of claim 1, whereinutilizing the channel access mechanism comprises: utilizing the channelaccess mechanism to select the set of time-frequency resources for thetransmission of the packet based at least in part on iterating the valueof the CAC to the trigger value.
 11. The method of claim 10, wherein thechannel access mechanism includes at least one of: a random resourceselection mechanism, a listen-before-talk (LBT)-based mechanism, or acombination of the random resource selection mechanism and the LBT-basedmechanism.
 12. The method of claim 1, wherein iterating the value of theCAC comprises: iterating the value of the CAC by a fractional value of aquantity of time-frequency resources available in a slot.
 13. The methodof claim 12, wherein the fractional value is based at least in part on aquantity of available time-frequency resources in the slot that has anamount of energy that satisfies a configured threshold.
 14. The methodof claim 13, wherein the configured threshold is pre-configured via aradio resource control (RRC) configuration.
 15. The method of claim 1,wherein iterating the value of the CAC comprises: iterating the value ofthe CAC by a multiple of a fractional value of a quantity oftime-frequency resources available in a slot.
 16. The method of claim15, wherein the multiple is a non-fractional value.
 17. The method ofclaim 15, wherein the multiple is another fractional value.
 18. Themethod of claim 15, wherein the multiple is based at least in part on atleast one of: a priority associated with the packet, a quality ofservice (QoS) value associated with the packet, or a combination of thepriority and the QoS value.
 19. The method of claim 18, wherein thepriority associated with the packet, the QoS value associated with thepacket, or the multiple are pre-configured via a radio resource control(RRC) configuration.
 20. The method of claim 1, wherein the size of thetransmission window for the transmission of the packet, or a multiple ofa fractional value of a quantity of time-frequency resources availablein a slot, are based at least in part on at least one of: a channel busyratio (CBR) for the slot to be used for the transmission of the packet,a priority of the packet, a quality of service (QoS) value of thepacket, or a combination of the CBR for the slot, the priority of thepacket, and the QoS value of the packet.
 21. The method of claim 1,wherein an amount by which the value of the CAC is iterated is based atleast in part on at least one of: a channel busy ratio (CBR) for a slotto be used for the transmission of the packet, a priority of the packet,or a combination of the CBR for the slot and the priority of the packet.22. A first wireless communication device for wireless communication,comprising: a memory; and one or more processors configured to: iteratea value of a channel access counter (CAC) based at least in part on astarting value of the CAC, wherein the starting value is based at leastin part on a size of a transmission window; determine that the value ofthe CAC satisfies a trigger value; utilize a channel access mechanism toselect a set of time-frequency resources for a transmission of a packetbased at least in part on the value of the CAC satisfying the triggervalue; and transmit the packet to a second wireless communication devicevia the selected set of time-frequency resources.
 23. The first wirelesscommunication device of claim 22, wherein the one or more processors arefurther configured to: configure the value of the CAC for the packetprior to iterating the value of the CAC.
 24. The first wirelesscommunication device of claim 22, wherein the one or more processors arefurther configured to: determine, prior to iterating the value of theCAC, a quantity of candidate resources that is available in a slot,wherein a candidate resource has a size equal to a quantity oftime-frequency resources to be used for the transmission of the packet.25. The first wireless communication device of claim 22, wherein, inconfiguring to iterate the value of the CAC, the one or more processorsare configured to: iterate the value of the CAC by an amount equal to atleast one of: a quantity of elapsed candidate resources available in aslot, a quantity of elapsed available slots associated with atransmission window, or a combination of the quantity of elapsedcandidate resources and the quantity of elapsed available slots.
 26. Thefirst wireless communication device of claim 22, wherein, in configuringto utilize the channel access mechanism, the one or more processors areconfigured to: utilize the channel access mechanism to select the set oftime-frequency resources for the transmission of the packet based atleast in part on iterating the value of the CAC to the trigger value.27. The first wireless communication device of claim 22, wherein, inconfiguring to iterate the value of the CAC, the one or more processorsare configured to: iterate the value of the CAC by a fractional value ofa quantity of time-frequency resources available in a slot.
 28. Anon-transitory computer-readable medium storing one or more instructionsfor wireless communication that, when executed by one or more processorsof a first wireless communication device, cause the one or moreprocessors to: iterate a value of a channel access counter (CAC) basedat least in part on a starting value of the CAC, wherein the startingvalue is based at least in part on a size of a transmission window;determine that the value of the CAC satisfies a trigger value; utilize achannel access mechanism to select a set of time-frequency resources fora transmission of a packet based at least in part on the value of theCAC satisfying the trigger value; and transmit the packet to a secondwireless communication device via the selected set of time-frequencyresources.
 29. The non-transitory computer-readable medium of claim 28,wherein the size of the transmission window is based at least in part onat least one of: a quantity of candidate resources that is available ina slot, a quantity of slots associated with the transmission, or acombination of the quantity of candidate resources that is available inthe slot and the quantity of slots associated with the transmission. 30.The non-transitory computer-readable medium of claim 28, wherein the oneor more instructions further cause the one or more processors to:configure the value of the CAC for the packet prior to iterating thevalue of the CAC.
 31. The non-transitory computer-readable medium ofclaim 28, wherein the trigger value is between zero and the size of thetransmission window.
 32. The non-transitory computer-readable medium ofclaim 28, wherein the size of the transmission window for thetransmission of the packet, or a multiple of a fractional value of aquantity of time-frequency resources available in a slot, are based atleast in part on at least one of: a channel busy ratio (CBR) for theslot to be used for the transmission of the packet, a priority of thepacket, a quality of service (QoS) value of the packet, or a combinationof the CBR for the slot, the priority of the packet, and the QoS valueof the packet.
 33. The non-transitory computer-readable medium of claim28, wherein an amount by which the value of the CAC is iterated is basedat least in part on at least one of: a channel busy ratio (CBR) for aslot to be used for the transmission of the packet, a priority of thepacket, or a combination of the CBR for the slot and the priority of thepacket.
 34. An apparatus for wireless communication, comprising: meansfor iterating a value of a channel access counter (CAC) based at leastin part on a starting value of the CAC, wherein the starting value isbased at least in part on a size of a transmission window; means fordetermining that the value of the CAC satisfies a trigger value; meansfor utilizing a channel access mechanism to select a set oftime-frequency resources for a transmission of a packet based at leastin part on the value of the CAC satisfying the trigger value; and meansfor transmitting the packet to a wireless communication device via theselected set of time-frequency resources.